One of the major problems encountered by a firefighter is stress. One of the major causes of stress in a firefighter pertains to the weight of the garments worn by the firefighter. One of the garments worn by a firefighter is a helmet.
Conventionally, a firefighter's helmet comprises a rigid outer layer or shell which covers a resilient, deformable intermediate layer surrounding an inner molded plastic impact cap. The principal purpose of the shell is to provide strength and resistance to impact and resistance to penetrating forces and objects, while that of the intermediate layer is to absorb shock.
To achieve the desired strength and impact resistance qualities, the shell of the firefighter's helmet is conventionally made of a composite, fiber-reinforced plastics material, such as a glass fiber reinforced polyester resin. Fiber materials are positioned within molded polyester resin materials. The fiber materials may be in the form of glass type single fibers mixed into the resin or a mat of glass fibers impregnated with resin and/or woven glass cloth impregnated with resin. The shell may have only one type of reinforcement materials or a combinaton of two or more types of reinforcement materials.
The strength and impact resistant qualities of the shell are directly related to the reinforcement materials within the resin of the shell. The resin, which is the heaviest material in the shell, provides no strength or impact or penetration qualities to the shell. Such qualities relate only to fiber material within the resin material.
It is equally important, however, that the shell be able to withstand and retard the transmission of heat, not only for the maintenance of its own integrity in highly heated environments but also for the protection of the intermediate layer which is conventionally composed of a urethane foam material. If the shell does not resist the heat properly, the heat will penetrate the shell and cause partial disintegration of the urethane foam of the intermediate layer. When this occurs the helmet loses its shock absorbing capability.
The mass created by the polyester resin has a definite effect in this critical area. That is, the less mass in the polyester resin, the greater the heat penetration through the helmet and thus the less effective heat protection in the helmet.
A problem exists in regard to reducing the weight of a firefighter's helmet by reducing the mass of the polyester resin, without reducing the heat resistant qualities of the outer shell.
It is therefore an object of this invention to provide a firefighter's helmet which has minimum weight while also providing good thermal protection.
It is another object of this invention to provide such a firefighter's helmet which has excellent impact resistant and shock absorbing qualities under both high heat and low heat conditions.
Other objects and advantages of this invention reside in the construction of parts, the combination thereof, the method of production and the mode of use, as will become more apparent from the following description.